A variety of important studies — but no stunning headliner — will be presented at the 35th Annual San Antonio Breast Cancer Symposium (SABCS), being held December 4 to 8 in Texas, according to one of its codirectors.
“It’s a little less obvious this year,” said Peter Ravdin, MD, PhD, about which studies will garner the most attention from clinicians.
However, Dr. Ravdin, who is director of the Comprehensive Breast Health Clinic at the Cancer Therapy & Research Center, University of Texas Health Science Center at San Antonio, reviewed a number of this year’s contenders in an interview with Medscape Medical News.
The international ATLAS (Adjuvant Tamoxifen, Longer Against Shorter) study asks a “classic question” in medical research, said Dr. Ravdin: “Is longer [use of a therapy] better?”
The study (presentation S1-2) of women with estrogen-receptor (ER)-positive early breast cancer compares 5 years of tamoxifen with 10 years of the antiestrogen for 2 primary outcomes: recurrence and disease-specific survival. Five years of tamoxifen use has been proven to reduce recurrence and breast cancer mortality for a period of a decade or so, said Dr. Ravdin. “Should we consider using tamoxifen for longer than 5 years?” he asked. “If so, is toxicity a concern?”
The study results “may cause a rethinking of how we treat postmenopausal women in particular,” Dr. Ravdin said.
Notably, ATLAS is the only oral presentation at this year’s conference that will have a discussant, which is typically an indicator of the weight of a study.
The CALOR (Chemotherapy as Adjuvant for Locally Recurrent Breast Cancer) trial is a “great study” because it will clarify whether a current practice in the setting of recurrent disease is useful, Dr. Ravdin said.
The trial (presentation S3-2) looks at the use of chemotherapy in patients who undergo surgical treatment for isolated local and/or regional recurrence. “We don’t know whether giving chemotherapy so long after a primary diagnosis can improve outcome,” he said. “It’s never been studied.”
There will also be new 10-year efficacy data on trastuzumab plus adjuvant chemotherapy in the treatment of HER2-postive disease (presentation S5-5). “This is the first long-term overall survival data for [trastuzumab],” said Dr. Ravdin. These data come from the North American NSABP B-31 and NCCTG N9831 trials.
Also of “high interest to clinicians,” he said, are the 10-year follow-up results from the British Standardization of Breast Radiotherapy Trials (START), which compare hypofractionated and standard 5-week courses of radiotherapy in the treatment of local-regional early breast cancer. The presentation will look at the safety and efficacy of the different approaches.
Vying for attention among these larger, more mature studies is a phase 2 study of PD 0332991, a cyclin-dependent kinase 4/6 inhibitor, Dr. Ravdin noted.
The results of that study will be presented in one of the general sessions (presentation S1-6). The experimental agent in combination with letrozole is compared with letrozole alone in the first-line treatment of ER-positive/HER2-negative advanced breast cancer. “These results are awaited with real interest,” Dr. Ravdin explained, because clinicians need an alternative to bevacizumab, which is “very expensive” and has “significant toxicities” in some patients. Bevacizumab was rescinded by the US Food and Drug Administration last year for use in advanced breast cancer.
Nevertheless, bevacizumab is the focus of the phase 3 LEA trial (presentation S1-7), which evaluates its addition to endocrine therapy as first-line treatment for advanced breast cancer. These are the first efficacy results from this Spanish and German study.
According to Kathy Miller, MD, who writes the Miller on Oncology blog for Medscape Medical News, there are 2 surgery trials that are potentially important.
The studies “will further define the role of sentinel node biopsy in a group of patients who often are not offered sentinel node biopsy in the community” or in any location where there are scheduling challenges to integrating this treatment, said Dr. Miller, who is from the Indiana University in Indianapolis.
The ACOSOG Z1071 trial (presentation S2-1) looks at the role of sentinel lymph node surgery in patients presenting with node-positive breast cancer (T0-T4, N1-2) who receive neoadjuvant chemotherapy.
“In this trial, all of those patients then undergo a full node dissection, which will allow us to define the detection rate and the false-negative rate in these patients who, according to current guidelines, would be excluded from having a sentinel node biopsy,” said Dr. Miller.
The second study is the European trial known as SENTINA (presentation S2-2). It provides final results and examines sentinel lymph node biopsy before and after neoadjuvant chemotherapy.
“Together, these studies have the potential to improve our ability to apply the sentinel node technique and to limit axillary and arm toxicity; there is a large group of patients for whom that is currently not possible,” said Dr. Miller.
— Nick Mulcahy0